The spectra obtained from the off-line non-contact configuration yielded a prediction performance comparable to the off-line contact method, with R2¼0.89 and RMSECV¼1.23 (5 PLS factors). The difference in performance was not significant (p¼0.482). SNVtransformed spectra and regression coefficients can be seen in Fig. 1b. It should be noted that the regression coefficients are found to be very similar to those found for the off-line contact measurements, which indicates that the non-contact configuration does not significantly alter the output of the NIR measurements. The ability to perform non-contact measurements is essential in order to develop a procedure for on-line measurements.